java在连接到JDBC时使用getColumnClass（）对JTable进行排序

Question

我花了几天时间试图正确地进行JTable排序。我知道我必须使用的代码，但似乎无法将其“适合”并应用到我的代码中。我从数据库获取TableModel数据，因此，如果在初始化模型时调用getColumnClass（），我会得到一个NullPointerException（当然），但我似乎无法让getColumnClass（int）在其他任何地方工作，比如model。getColumnClass（columnIndex）。我只需要按照数字顺序对第一列进行排序，因为其余的都是字符串。这是我的密码。（注：这是我第一次使用JBDC，所以我很可能在通话顺序上有错误——或者可能是用“直截了当”的方式，哈哈）

    public JTable memberList() 
        {
            JTable jTable1;
            DefaultTableModel model;
            model = new DefaultTableModel(); 
            jTable1 = new JTable(model);
            TableRowSorter sorter = new TableRowSorter(model);

            try 
            {
                Statement stmt = conn.createStatement();
                String sql = "select    rm.race_no,cm.firstname,cm.lastname,cm.phone,cm.dob,cm.email,cm.TwinTown_ID,rm.disqualified,cm.notes\n" +
                             "from competitor_master cm join competitor_season cs on cm.competitor_id = cs.competitor_id\n" +
                             "inner join race_master rm on cs.race_no= rm.race_no where cm.twintown_id is not null and cs.season_start_year in (year(sysdate()))\n" +
                             "group by (race_no);";
                ResultSet rs = stmt.executeQuery(sql);

                String b = "", c = "", d = "", e = "", f = "", g = "", h = "", i = "";
                int a;

                model.addColumn("Member Number");
                model.addColumn("First Name");
                model.addColumn("Last Name");
                model.addColumn("Phone");
                model.addColumn("Date of Birth");
                model.addColumn("Email");
                model.addColumn("TT Member Number");
                model.addColumn("Disqualified");
                model.addColumn("Notes");


                while(rs.next())
                {
                    a = rs.getInt(1);
                    b = rs.getString("FirstName");
                    c = rs.getString("LastName");
                    d = rs.getString("phone");
                    e = rs.getString("dob");
                    f = rs.getString("email");
                    g = rs.getString("TwinTown_ID");
                    h = rs.getString("disqualified");
                    i = rs.getString("notes");
                    model.addRow(new Object[] {a,b,c,d,e,f,g,h,i});
                    model.getColumnClass(1);

                }

                stmt.close();
                rs.close();

            }
            catch (SQLException ex)
            {

            }

                jTable1.getTableHeader().setFont(new Font("Microsoft Tai Le", Font.BOLD, 14));
                jTable1.getTableHeader().setBackground(Color.WHITE);
                jTable1.getTableHeader().setForeground(new Color(234, 168, 82));
                jTable1.getTableHeader().setBorder(null);


            jTable1.setRowSorter(sorter);
            return jTable1;

        }

    public Class getColumnClass (int column){
            if (column==1) {
                return(Integer.class);
            }
            return(String.class);
        }